Effect of grain size on low-temperature electrical resistivity and thermal conductivity of pure magnesium

2018 ◽  
Vol 229 ◽  
pp. 261-264 ◽  
Author(s):  
Xin Tong ◽  
Guoqiang You ◽  
Yuhan Ding ◽  
Hansong Xue ◽  
Yichang Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Pure Magnesium

Thermal Active Zone space-time evolution: a small-scale monitoring of thermal and electrical conductivity

2021 ◽  
Author(s):  
Alberto Carrera ◽  
Jacopo Boaga ◽  
Paolo Scotton ◽  
Antonio Galgaro
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Porous Medium ◽  
Electrical Resistivity ◽  
Active Zone ◽  
Time Lapse ◽  
Heat Pumps ◽  
Thermal Plume ◽  
Ground Source Heat Pumps ◽  
Ground Source

<p>The growing demand for renewable energy leads to an increase in the development of alternative energy applications. In this way, shallow geothermics assumes an important role in the global energy transition of building air conditioning. The design of Ground Source Heat Pumps (GSHP) requires a multidisciplinary approach including a good understanding of the underground geological setting, such as hydrogeological aspects and heat flow conditions. Classic monitoring strategies often rely on local and point-based measurements to monitor changes of underground temperature in time, with the limit of not succeeding in a whole delimitation of the Thermal Active Zone (TAZ). In this context, Electrical Resistivity Tomography (ERT) can bring relevant information on the temperature distribution for monitoring the induced thermal plume within BHEs (Borehole Heat Exchangers) systems. Geophysics helps the understanding of the thermal processes, in order to front the difficulties arising from Ground Source Heat Pumps (GSHP) implementation. Thermal conductivity and electrical resistivity depend equally in a complex way on different common subsurface and environmental attributes such as, among the main, mineralogical composition, grain size, density, porosity and saturation. Besides, thermal conductivity increases significantly with temperature in wet ground, by making it clear a relationship between both parameters.</p><p>ERT is particularly sensitive to the porous medium temperature and, when applied in time-lapse (TL), could provide spatially distributed information on the changes over time of water content, salinity or temperature. For this reason, in this work we monitored the complex TAZ temporal evolution during a heat injection experiment using a 3D time-lapse ERT survey, arranged in a reduced scale physical model. For a better understanding of measured electrical resistivity values, focused on mapping the extent of a geothermal plume around a borehole, a specific laboratory device was utilized. Grain size distribution, bulk density and saturation of the porous medium are known and established, as well as reliable temperature values acquired through sensors with which calibrate the ERT results. Thus, changes in resistivity can be interpreted to track the evolution of the plume of heated water and used to estimate the temperature change. The propagation of the heat plumes into the ground is also highly sensitive to interstitial water flow rate, thus also this condition was recreated and monitored varying the hydraulic gradient in the experimental device.</p><p>The present work aims to demonstrate the ability of ERT to provide complementary insights about the sub-surface spatio-temporal dynamic for monitoring the extension of TAZ caused by BHEs probes. In addition, the detailed scale adopted and the variable control within a laboratory setup ease the study of the interaction between thermal and electrical properties.</p>

THE LOW-TEMPERATURE THERMAL CONDUCTIVITY, ELECTRICAL RESISTIVITY, AND THERMOELECTRIC POWER OF DILUTE SILVER ALLOYS WITH MANGANESE

1966 ◽  
Vol 44 (10) ◽  
pp. 2293-2302 ◽  
Author(s):  
H. L. Malm ◽  
S. B. Woods
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Thermoelectric Power ◽  
Electron Scattering ◽  
The Other ◽  
Temperature Measurements ◽  
Silver Alloys ◽  
Temperature Range ◽  
Dilute Alloy

Low-temperature measurements of electrical resistivity, thermal conductivity, and thermoelectric power on silver alloys containing 0.005, 0.067, 0.11, and 0.31 at.% of manganese are reported. The same specimens were used for the measurement of all properties over the temperature range from 2 to 25 °K. The well-known minimum and maximum are observed in the electrical resistivity of the three more concentrated alloys and the minimum is visible in the most dilute alloy near the lowest temperatures of measurement. Associated effects are observed in the other properties and their possible relationship to theoretical electron scattering mechanisms, particularly that of Kondo, is discussed.

scholarly journals Low Temperature Transport Properties of the Group V Semimetals

1979 ◽  
Vol 32 (6) ◽  
pp. 585 ◽  
Author(s):  
J-P Issi
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Band Structure ◽  
Transport Properties ◽  
Phonon Scattering ◽  
Group V ◽  
Bismuth Antimony ◽  
Ultralow Temperatures ◽  
Rhombohedral Symmetry

The group V semimetals are first introduced by comparing their particular band structure with the more familiar typical metals or semiconductors. Recent results on the electrical resistivity, thermal conductivity and thermopower of bismuth, antimony and arsenic are reviewed, with particular emphasis on measurements performed at low and ultralow temperatures. The data are analysed in terms of the peculiar features of the electron and phonon scattering, and reference is made to the band structure and rhombohedral symmetry. Recent improvements in the interpretation of the results are discussed.

Physical Property Evaluation for High Purity Niobium and Tantalum Rare Metals

2007 ◽  
Vol 26-28 ◽  
pp. 1059-1062 ◽  
Author(s):  
Il Ho Kim ◽  
Jung Il Lee ◽  
G.S. Choi ◽  
J.S. Kim
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Temperature Dependence ◽  
High Purity ◽  
Phonon Scattering ◽  
Physical Property ◽  
Rare Metals ◽  
Metallic Behavior ◽  
Property Evaluation

Thermal, electrical and mechanical properties of high purity niobium and tantalum refractory rare metals were investigated to evaluate the physical purity. Higher purity niobium and tantalum metals showed lower hardness due to smaller solution hardening effect. Temperature dependence of electrical resistivity showed a typical metallic behavior. Remarkable decrease in electrical resistivity was observed for a high purity specimen at low temperature. However, thermal conductivity increased for a high purity specimen, and abrupt increase in thermal conductivity was observed at very low temperature, indicating typical temperature dependence of thermal conductivity for high purity metals. It can be known that reduction of electron-phonon scattering leads to increase in thermal conductivity of high purity niobium and tantalum metals at low temperature.

scholarly journals Low-temperature electrical resistivity and thermal conductivity of binary magnesium alloys

2014 ◽  
Vol 80 ◽  
pp. 288-295 ◽  
Author(s):  
Tao Ying ◽  
Hang Chi ◽  
Mingyi Zheng ◽  
Zitong Li ◽  
Ctirad Uher
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Magnesium Alloys

LSCO Ceramics as Possible Thermoelectric Material for Low Temperature Applications

2007 ◽  
Vol 1044 ◽  
Author(s):  
Julio E. Rodríguez
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Low Temperature ◽  
Seebeck Coefficient ◽  
Annealing Time ◽  
Oxygen Stoichiometry ◽  
Measured Temperature ◽  
Total Thermal Conductivity ◽  
Metallic Behavior ◽  
Temperature Range

AbstractSeebeck coefficient S(T), thermal conductivity κ(T) and electrical resistivity ρ(T) measurements on polycrystalline La1.85Sr0.15CuO4-δ(LSCO) compounds grown by solid-state reaction method were carried out in the temperature range between 100 and 290K. The obtained samples were submitted to annealing processes of different duration in order to modify their oxygen stoichiometry. The Seebeck coefficient is positive over the measured temperature range and its magnitude increases with the annealing time up to reach values close to 150 µV/K. The electrical resistivity exhibits a metallic behavior, in all samples, ρ(T) takes values less than 1mΩ-cm. As the annealing time increases, the total thermal conductivity increases up to values close to 3 W/K-m. From S(T), κ(T) and ρ(T) data, the thermoelectric power factor (PF) and the dimensionless figure of merit (ZT) were determined. These parameters reach maximum values around 25 µW/K2-cm and 0.18, respectively. The observed behavior in the transport properties become these compounds potential thermoelectric materials, which could be used in low temperature thermoelectric applications.

Transport Properties of the Ferromagnetic Metals. I. Cobalt

1973 ◽  
Vol 51 (12) ◽  
pp. 1247-1256 ◽  
Author(s):  
M. J. Laubitz ◽  
T. Matsumura
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Low Temperature ◽  
Theoretical Analysis ◽  
Coefficient Of Thermal Expansion ◽  
Ferromagnetic Metals ◽  
Band Structure Calculations ◽  
Structure Calculations

The thermal conductivity, electrical resistivity, and thermoelectric power of well-characterized, polycrystalline specimens of pure Co have been determined in the temperature range of 90 to 1250 K. Additionally, the measurements of the electrical resistivity have been extended to 1750 K, and the coefficient of thermal expansion measured between 300 and 770 K. The new results are compared with those previously published, and, for the low temperature h.c.p. phase, compared with predictions based on published band structure calculations. Qualitatively, the observed results agree with the predictions, particularly as far as the very unusual temperature variation of the Lorenz function is concerned; quantitative comparisons, however, are impossible, due to the lack of precision in the calculated band structures. The theoretical analysis of the results for the high temperature f.c.c. phase will be given together with that of Ni in Part II.

Thermal Conductivity and Electrical Resistivity in Polycrystalline and Nanocrystalline Nickel

2011 ◽  
Vol 409 ◽  
pp. 561-565 ◽  
Author(s):  
S. Wang ◽  
I. Brooks ◽  
J.L. McCrea ◽  
G. Palumbo ◽  
G. Cingara ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Electrical Resistivity ◽  
Flash Method ◽  
Pulsed Current ◽  
Polycrystalline Nickel ◽  
Nanocrystalline Nickel ◽  
Annealed Condition ◽  
Grain Sizes ◽  
The Relationship

The grain-size dependences of thermal conductivity and electrical resistivity of polycrystalline and nanocrystalline nickel were measured by the flash method and four-point probe method, respectively. Nanocrystalline nickel (grain size: 28 nm) was made by the pulsed-current electrodeposition process, while polycrystalline nickel (grain size: 57 μm) was the same material in fully annealed condition. Noticeable differences in thermal conductivity and electrical resistivity were observed for both materials. These results can be explained on the basis of the rapid increase in the intercrystalline grain boundary and triple junction volume fractions at very small grain sizes. The relationship between thermal conductivity and electrical resistivity of nanocrystalline nickel follows the classic Wiedemann-Franz law.

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